The present invention relates to an impact crusher having a rotor carrying a number of breaker bars for comminuting particulate material, such as rock, ore, limestone, grain, concrete or the like, and more particularly, to an improved means for securing the breaker bars to the rotor, and means for permitting easy access into the crusher and for easy removal and installation of the breaker bars.
In impact crushers, it is well-known to provide a rotor with several replaceable breaker or impact bars mounted onto the periphery of the rotor, which may be of the open disc-type consisting of generally several disc plates mounted on a rotatable shaft. In the present open disc-type rotor, both the back-up bar and breaker bar extend between opposed disc plates. The back-up bar is welded in the opposed discs, and may either have an angular protrusion which fits into a similarly formed depression in the breaker bar as shown in U.S. Pat. No. 3,531,055 or may have an angularly formed depression for receiving a similarly formed protrusion of the breaker bar. The breaker bar is held in position by inserting a breaker bar holder or shoe against a nose of the disc plate between the breaker bar and disc plate.
During rotation of the shaft and discs, severe centrifugal forces are exerted against the sloped protrusions and depressions in the breaker bar or back-up bar, and severe lateral forces are ultimately exerted against the shoe resulting in a skewed seating for the breaker bar, and thus, reduced contact support between the breaker bar with a bottom edge of the shoe and also between the breaker bar with an upper edge of the back-up bar and between the depression and protrusion area of the breaker bar and back-up bar to the extent of insufficient support and eventual damage to the back-up bar protrusion and the disc nose.
This present design for replaceable breaker bars is extremely unconducive in establishing and maintaining self-alignment of the back-up bar, breaker bar, and shoe, and frequently results in deformation of the back-up bar and the rotor disc nose which are normally considered to be nonreplaceable components. This deformation condition of the back-up bar and disc nose often requires repair by weld built-up or machining of these fixed parts, which translates into extended downtime of the impact crusher and excessive maintenance manpower hours.
In addition, these present day designs of an impact crusher features either a substantially closed housing with only a small door in the impactor sidewall providing minimal access to the rotor and breaker bars, or an opened housing where a rear portion is hinged for pivotal movement, in which case, access to the rotor and breaker bars is improved.
However, in these housing designs as well as others it is to be appreciated that the breaker bar during its replacement is located in an undesireable position in that the back-up bar provides little or no support for the breaker bar during its installation or removal. Again, the results translates into extended downtime of the impact crushers and excessive manpower hours.
None of the present day impactor designs provides a locking device for simultaneously holding the rotor in place while at the same time providing support for the breaker bar during its removal from and installation into the housing.